In our continuing series looking at the latest medical research and news on COVID-19, Larry Mantle speaks with Dr. Dean Blumberg, professor of medicine and chief of Pediatric Infectious Diseases at UC Davis Children’s Hospital.  Topics today include:  Experts say the U.S. is likely “dramatically undercounting” current COVID cases as states scale back regular reporting.  Coronavirus cases on the rise in L.A. County, prompting concerns for spring break.  What we know about the Omicron XE subvariant in California.  California removes quarantine requirement for asymptomatic people exposed to COVID.  Pfizer says its booster raises antibodies against Omicron in kids 5-11.  C.D.C. extends mask mandate on planes, trains until May 3.  The city of Philadelphia will reinstate its indoor mask mandate.  This program is made possible in part by the Corporation for Public Broadcasting, a private corporation funded by the American people.